Samsung’s Galaxy Note 7 battery issue was never properly diagnosed when the first round of recall and replacement was issued. The company rushed to get the phone out to the market without actually figuring out what was causing the phone to explode. A new report in Wall Street Journal has highlighted how Samsung executives didn’t have a final answer on what caused the phones to explode and rushed with the replacement units.

The new report says Samsung’s lab scans showed a bulge in the battery of some of the faulty devices, and it was wrongly concluded this was due to the batteries “supplied by Samsung SDI Co.” According to the report, Samsung’s new mobile chief D J Koh felt this was enough evidence to push for a recall and replace the phones, despite lack of conclusive evidence. Now with the Galaxy Note 7’s production dead, Samsung has still not given any answer on what caused the issue.

An earlier report in the New York Times had also revealed how Samsung’s own engineers were unable to re-create the problems in their own labs, which added to the problem of incorrectly diagnosing the issue. With pressure on to replace the units, the blame was fixed on a set of faulty batteries, and new phones were issued towards end of September. However, that back-fired as even these phones continued to catch fire, and explode in some cases.

But there’s more troubling news for Samsung, according to the latest WSJ report. The report goes on to add the US Consumer Product Safety Commission is “expected to investigate whether Samsung notified the agency soon enough of dangers posed by the device.” When reports first emerged in September of exploding Note 7 Samsung didn’t call for an immediate recall and eventually it didn’t go with “US CPSC’s formal process for a time.” Had Samsung gone with the latter, regulators would have had more time to narrow down on the exact cause.

The report also says Samsung engineers were exploring if the battery case was too small for the capacity.

It seems the Note 7 fiasco has highlighted the dangers of the lithium ion batteries with the US CPSC Chairman Elliot Kaye convinced there will be another issue due to these. According to WSJ, the agency has “approved a proposal for a wide-ranging inquiry into lithium ion and related batteries in coming months.”

For Samsung, the Galaxy Note 7 fiasco is costing the company close to $5.3 billion in this quarter and the coming ones. Samsung will end all marketing campaigns around Note 7, which was expected to be the company’s challenger to the iPhone 7 Plus. It remains to be seen whether the Note brand survives and gets a revival in 2018. For now, all eyes will be on how Samsung’s next flagship the Galaxy S8 performs.